In the rich text editor:
@JustaLittleSyn
In a comment:
[JustaLittleSyn](https://chowlings.com/user/JustaLittleSyn)
For Names and Avatars:
In the rich text editor:
%JustaLittleSyn
In a comment:
[![JustaLittleSyn's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/JustaLittleSyn) [JustaLittleSyn](https://chowlings.com/user/JustaLittleSyn)